How to Make It
Preheat oven to 400°F.
Place beets on a large piece of foil; bring edges of foil to center. Add 1 tablespoon water to beets; crimp edges of foil to seal. Bake for 1 hour or until beets are tender when pierced with a fork. Remove foil; discard. When cool enough to handle, peel beets, and thinly slice using a mandoline or sharp knife.
Roll out puff pastry sheet to a 14- x 12-inch rectangle on a large piece of parchment paper. Place parchment paper with puff pastry on a baking sheet. Score a 1-inch border around edge of puff pastry with a paring knife; prick area inside border several times with a fork. Bake pastry for 14 minutes or until light golden, and remove from oven.
Arrange beet slices over puff pastry, inside border, so that slices overlap by about 1/2 inch. Bake for 12 minutes or until crust is golden brown. Brush orange juice over beets; drizzle with honey. Sprinkle hazelnuts, thyme, salt, and goat cheese over tart. Cut into 12 slices.